Capacitive temperature and pressure transducer
First Claim
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1. Apparatus for measuring and comparing pressures, comprising:
- (a) means for detecting a temperature variation and for providing a temperature sensor signal representative of the temperature variation;
(b) means for sensing an absolute pressure and for providing an absolute sensor signal representative of the absolute pressure;
(c) means for sensing a differential pressure and for providing a differential sensor signal representative of the differential pressure;
(d) means for selecting one of said temperature detecting means, absolute pressure sensing means or differential pressure sensing means for reading the respective sensor signal of the selected means;
(e) means responsive to the selecting means for comparing the temperature sensor signal to the differential sensor signal and for generating a first comparative signal representative of the ratio between the temperature sensor signal and the differential sensor signal; and
(f) means responsive to the selecting means for comparing the temperature sensor signal to the absolute sensor signal and for generating a second comparative signal representative of the ratio between the temperature reference signal and the absolute sensor signal.
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Abstract
A monolithic temperature and pressure transducer having a plurality of capacitive sensors. The capacitors are formed from the same silicon substrate and are equally affected by temperature variations, including temperature gradients.
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Citations
18 Claims
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1. Apparatus for measuring and comparing pressures, comprising:
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(a) means for detecting a temperature variation and for providing a temperature sensor signal representative of the temperature variation; (b) means for sensing an absolute pressure and for providing an absolute sensor signal representative of the absolute pressure; (c) means for sensing a differential pressure and for providing a differential sensor signal representative of the differential pressure; (d) means for selecting one of said temperature detecting means, absolute pressure sensing means or differential pressure sensing means for reading the respective sensor signal of the selected means; (e) means responsive to the selecting means for comparing the temperature sensor signal to the differential sensor signal and for generating a first comparative signal representative of the ratio between the temperature sensor signal and the differential sensor signal; and (f) means responsive to the selecting means for comparing the temperature sensor signal to the absolute sensor signal and for generating a second comparative signal representative of the ratio between the temperature reference signal and the absolute sensor signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. In a system for measuring the pressure of a process fluid and for correcting the measurements for temperature variations, the improvement comprising:
a capacitive sensor for detecting temperature variations. - View Dependent Claims (17)
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18. In a system for measuring the pressure of a process fluid and for correcting the measurements for temperature variations, the improvement comprising:
a monolithic capacitive sensor structure having a capacitor for determining temperature variations, a capacitor for determining an absolute pressure and a third capacitor for determining a differential pressure between the absolute pressure and a second pressure.
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